He started both games of a September 28 doubleheader with the New York Yankees, one at short and the other at second, and collected his first major league hit off Larry Gura in the second game.[3] He returned to the triple A Rochester Red Wings in 1976, and again received a call up to the majors that September. In total, Bailor batted .288 with twelve home runs and 201 runs batted in over seven seasons in the Orioles' farm system. He was three-for-thirteen with no home runs or RBIs at the major league level.

After the Seattle Mariners selected Ruppert Jones from the Kansas City Royals with the first overall pick in the expansion draft, the Toronto Blue Jays made Bailor the second overall pick.[4] Despite the fact that he did not have an everyday position, Bailor appeared in 122 games, and logged 523 plate appearances his rookie season in Toronto. He led the team in hits, (154) stolen bases (15), runs scored (62), and his .310 batting average set an expansion team record.[5] He had ten assists from the outfield in just 537 innings, and was named to the ToppsRookie All-Star team at shortstop despite the fact that he only appeared in 53 games at short. On April 20, the New York Yankees' Sparky Lyle struck Bailor out for the first time in his major league career.[6] Bailor had batted a record 51 times before striking out for the first time.[7]

In 1978 & 1979, Bailor emerged as the Jays' regular right fielder, though he still played many different positions. In 1978, he drove in a career high 52 runs while striking out only 21 times in 621 at-bats. He was named the Blue Jays Player of the Year for the first two years of the franchise's existence.[8]

Bailor spent a month on the disabled list with a rib cage injury, and was used sparingly his first season in New York, appearing in 51 games and logging just 81 at-bats.[9] He went into Spring training1982 competing for either of the two middle infield positions,[10] and began the season competing with Wally Backman and Tom Veryzer for playing time at second base. With both Bailor and Backman batting over .300 at the end of May, Bailor began seeing more playing time at short and third. He ended the season with 404 plate appearances, his most since 1979. He also stole a career high 20 bases, and led the National League with an 87% stolen base percentage.

He began the 1983 season as the Mets' starting shortstop, and hit the only home run of his Mets career on April 13 against the Philadelphia Phillies' Sid Monge.[11] A sore left rib cage muscle landed Bailor on the disabled list at the start of May, and opened the door for Jose Oquendo to take over at shortstop. When Bailor returned later in the month, he was used more as a back-up infielder. For the season, he appeared in 118 games, his highest total since 1979. On December 8, Bailor was traded to the Los Angeles Dodgers in a deal that was very unpopular with Mets fans at the time. He and pitcher Carlos Diaz were shipped to the Dodgers for Sid Fernandez and Ross Jones.[12]

Bailor's first season in Los Angeles started late and ended early due to injuries. He dislocated his left shoulder during Spring training, causing him to miss the first month of the 1984 season. He then tore the cartilage in his right knee during batting practice on August 12 requiring arthroscopic surgery that pretty much ended his season.[13] He ended the season hitting .275 with 0 HR and 8 RBI in just 65 games. In 1985, Bailor hit .246 with 0 HR and 7 RBI in 74 games with Los Angeles, helping the team reach the post-season. In the 1985 NLCS against the St. Louis Cardinals, Bailor got into two games, going hitless in one at-bat, as the Dodgers lost to the Cardinals. On April 2, 1986, the Dodgers released Bailor.

Bailor's .310 batting average with the expansion Toronto Blue Jays broke Rusty Staub's record[clarification needed] set in 1969 with the Montreal Expos (.302). The two were teammates on the New York Mets from 1981 to 1983. Bailor wore number 4 with the Mets, Staub's number during his first tenure with the club (1972-1975). Though he proved to be one of the great utility players of his era, Bailor never liked the term. "It sounds like a guy who changes light bulbs."[14]

Shortly after his release from the Dodgers, Bailor was offered a player-coach position with Toronto's triple A affiliate, the Syracuse Chiefs. He turned the position down in order to spend time with his newborn child, Robert Michael, Jr. A year later, he accepted a position with the organization managing the Florida State League's Dunedin Blue Jays.[15] Bailor later went on to manage Syracuse from 1988 to 1991, and was named International League Manager of the Year as he led the Chiefs to a first-place finish.[16] From 1992 until 1995, Bailor served as a coach with the Toronto Blue Jays.[17]